Alternating-current motor.



M. C. A. LATOUR.

ALTERNATING CURRENT MOTOR.

APPLICATION rum) AUG. 17, 1907,

909, 1 93 Patented Jan. 12, 1909.

Witnesses. Inventor marius C.A.Lat :ur,

voltage impressed on their tcrfimincls.

UNITED STATES PATENT. ()lliiltiE.

Specification of Letteul Filter) t.

io'tentodqlo'n. 12, 1909.

Application M August 11. mm. Serial No. 388,991.

rent meters of. the commutator type, [111 arlhihh' an auxiliary commutoling {fie-l! is rdduced or balancing the elultrornotivc orhes induced in the moisture coils; shortmmimd by the brushes. o6! evobject of my invention is to provide liwndvl s rrangen ent of the connections of tlrei commiit'atmg coils adapted to give good olt'ni mutation'over wide ranges of speei'l. Kiln [on ultcriiatin -currentmotior of the cbriitnuta'tor ty e, the ormut-urc coils shortnhlouli tedhy the brushes ore snlijoctwgl to the woman field of the motor, so th at ltherc is p rolligced in these boils by transformer no ftiiin u voltage ninety degrees out of phase with theino torou rrvnt. For countsi imlnnc iiig iihi's voltage in the shori-oircui'tcd coils, iiilkhiiiiiiiiiUd-iiifl hold is requirecfl, inch is. htfifclcgrecs out of phase nit-h the motor lttifq'iifits, quid which mayconsequently he. produced by impressing on tho commumting soils-s voltage in phase with the inotor currents sinh -r the current in the comr'miiinting coils l'algs nearly ninety degrees heliinrirtlug a simple shuht connection. is employed for the commutating coils, the strength of the field produced by the commntcting coils remains constant, so that the voltage induced in the short-circuited armature coils, by cutting this field, incresses with the speed. The electromotive forces induced by transformer action in the short-circuited coils is indcpendent of the speed, and varies with the current, which tends to decrease as the. motor speed. increases. Therefore, a simple shunt connection with the commutatingcoils can ive good commutation for one speed only. y my invention an automatic regulation of the stren th of the auxiliary commutating field is 0 tsined, in accordance with the speed of the motor. I secure thisresult by impressing on the commutstin coils the resultn'nt of two voltages, ofwhio the smaller increases with increase of speed. The voltcge at the terminals'of the motor armature or a. voltage roportional thereto may be employed for t e smaller of the two opposing Lion of the livid of exciting coils B.

suitable source.

voltnges iniprvssml on iii! mmmlltiiting coll, since l'lw urimLtun-z voltage lIlC-I'OIWUH with tho il-icronse of speed: if'ilH'll nnarrange]hem. results in decreasing the strength ol- (h.- conunulnting field with lllt'l'luhtf 01' speed, so that good commutation isohmineil over a wide runge of speed.

My invention will host he understood h mime-nuto the ucconiponying (ii-"wings, in which- Figure l is un explmmtorydiagram, and Fig. 2 SlliH-Yh' the prolorreil minim-lions of tho Colltilllllll-l-lllg coil.

. in the drawings, A represents the armsture, B the lie-1d, C tho compensating lfltl ing of an alt-urnut-ingc-rn'rmil mufipensated series motor.

l) represent-i thv commutating coil or coils for 'lroducing' the (plummeting hold for neu- 5 trolizing the volt-ziggeinduced in tho slmrt- (ircirilml urnmture coils by transformer aid-- lithe coil I) is connected as shown. and iftho leads J are connected to a. suitable source of voluige opposing the voltiige of the motor arms-- ture between the. loads at, then the voltw e across the terminals of'thc coil'D will re 'v== \"--V, in which V? represents the +0)- ts-ge from the outside source; Lind. l the voltiigc across the armature ter'nfiinals. the voltage V increases with increase of speed, the voltage v, .ancl'c'onsc n'el itly the st'mn th of tho commntnting fie-dfwill r,l'iminis iwithincrease of speed. This decrease in the strength of the commutator field is necessary for cod. commutation over wide ranges of spear since, if the strength of the commuteting field should remain constant, the voltage induced'in the.short-circnitod coilliy euttin it would increase with increase of spent.

The voltage V may be. derived from any It is not necessary that this voltage should be cxsctly in phasewith the voltage across the armature terminals of the motor. There is a second source oil voltage in. the short-circuited snnaturc coils tending to produce sperking,"-viz., electromotive force of commutation-reactance, and this elcctromotive force which is in. phase with the armature current may be counterbalanced by sli htlv dephusing volts. e V with res 'cct to The phase of the 'vdltage V may e re latod in anv well known Way.

If, instea. of employing the annature Since Elf) voltage directly for regulating the strength of the commutating fie d, a smaller voltage proportional to the armature voltage is employed, the voltage V may be small and may is derived from the ohmic drop in a resistance in series with the motor. vSuch an arrangement is shown in Fig. 2, in which E represents a resistance in series with the motor, and F a small transformer, the .pri mary of which is in shunt tothe compensating and armature windings, while the secondary is in series with the commutating coil. The voltage dro across the resistance E, which correspon s to the voltage V of Fi 1, varies with the motor current only, ivqiile the voltage at the secondary terminals of transformer-F, corres ending to V in Fig. 1, is proportional to t e armature volta e, WhlOh varies both with the strength of fie d and consequently the motor current, and with the motor speed. The voltage across the commutatin coil which is maximum at starting, gradua 1y decreases as the motor speeds up, owing to the increase of voltage in transformer F.

I do not desire to limit myself to the particular connections here shown, but aim in the appended claims to cover all modifications which are within the scope of my invention.

What I claim as new and desire to secure by Letters Patent ofthe United States, is,-

1. In an alternating-current motor of the commutator type, a commutating coil, and

- connections therefor including means for impressing on the coil the resultant of two voltages, of which the smaller increases with increase of s eed. I

2. In an a ternating current motor of the commutator t pe, a commutating coil, and connections. therefor including means for scales voltage at the armature terminals.

ii an altemating-current motor of the commutator type, a commutating coil, a resistance in series with the motorand in shunt to said coil, and a source of voltage increasing with the speed of the motor 0])- posing the flow of current.through said coil due to the voltage drop in said resistance.

6. In an alternating-current motor of the commutator type, a commutating coil, a resistance in series with the motor and in shunt to said coil, and a transformer having its dprimary in shunt to the motor armature an its secondary in series with said coil.

7. In an alternating-current motor of the commutator type, a commutating coil, and

means for impressing on said coil the resultant of two opposing voltages one proportional to the motor current and the other proportional both to the moto eminent and to the speed. j

In witness whereof, I have hereunto set my hand this 12th day f Angus; 1907.

. MARI S G. A. LATOUR. Witnesses:

BENJAMIN B I'IULL, HELEN 03.1mm). 

